This study aims to prepare phosphotungstic acid supported on hydrotalcite (PTA-HT) for one-pot hydrothermal cellulose conversion into formic acid (FA). In this study, different percentages of PTA on HT (1, 5, 10, 15, 20, 25, and 33%) were prepared and the catalytic activity was observed for two different parameters such as time (1 to 5 hours) and reaction temperature (160 to 240 °C). The prepared catalysts were characterized using Fourier transform infrared (FTIR), X-ray powder diffraction (XRD), Brunauer-Emmet-Teller (BET) and field emission scanning electron microscopy-energy dispersive X-ray spectrometry (FESEM-EDX), while the production of FA was determined using ultra high-performance liquid chromatography (UHPLC). To avoid bias, raw PTA and calcined HT were compared with varying percentages of supported PTA. PTA-HT was successfully prepared through the impregnation method as confirmed by XRD, FTIR, BET and FESEM-EDX. According to the results, the optimum condition for cellulose conversion into formic acid was when 25% PTA-HT was applied at 220 °C for 4 hours, with a 30% cellulose conversion and 18 % FA yield. Due to the acidity and redox properties of PTA, it has been demonstrated that PTA-HT increased the catalytic activity by two-fold when compared to calcined HT alone (8%). The significance of this finding opens new suggestion of bifunctional catalyst in cellulose conversion into FA.

Cellulose, an abundant biomass, has received considerable attention as a renewable precursor to the formation of valuable chemicals. The overall strategy in this research is to produce formic acid from cellulose by using direct catalytic hydrothermal method. In this study, a heterogeneous catalyst system was developed by preparing different types of HPA on hydrotalcite. The three types of HPA- HT are phosphotungstic acid-hydrotalcite (PTA-HT), phosphomolybdic acid-hydrotalcite (PMA-HT) and silicotungstic acid-hydrotalcite (STA-HT); were prepared by the impregnation method. These prepared catalysts were characterized using FTIR, XRD and FESEM-EDX. The catalytic reaction was carried out in a hydrothermal reactor and the FA production was determined using HPLC-DAD. Comparison was made during the investigation where calcined HT was used for cellulose conversion and compared with each HPA-HT. All three catalysts were successfully impregnated on the calcined HT, as proven by XRD, FTIR, and EDX. According to the finding, PMA-HT give the highest cellulose conversion (48%) and FA yield (9.61%) followed by PTA-HT (32% converted cellulose with 7.35% FA yield) and STA-HT (17% cellulose converted and 2.87%). This phenomena occur due to the acidity and moderate redox properties of molybdenum in PMA. Herein, we reported effects of different HPAs on HT towards FA yield.

The chemical reduction progression behaviour of transition metals (Mo, Zr, W, Ce, and Co) doped on NiO was studied using temperature programmed reduction (TPR) analysis. A wet impregnation method was applied to synthesise the doped NiO series catalysts. The reduction progress of the catalysts was attained by using a reductant gas at the concentration of 40% v/v CO/N2. X-ray diffraction (XRD) was employed to determine the composition of the reduced phases. Undoped NiO was reduced at 384℃ to obtain a cubic phase of NiO. It was observed that Ce/NiO exhibited the lowest reduction temperature of 370℃ among all catalysts. This phenomenon might be due to a higher surface area of Ce/NiO compared to undoped NiO, which facilitated a faster reduction reaction. The rest of the doped NiO series catalysts (Co/NiO, Mo/NiO, W/NiO and Zr/NiO) demonstrated a higher reduction temperature compared to undoped NiO. New peaks in the XRD pattern were observed only for the reduced catalysts of Mo/NiO and W/NiO, which were associated with monoclinic MoO2 and WO2.72 phases, respectively. The formation of new compounds or more stable nickel alloys led to a slower reduction reaction than undoped NiO. Therefore, Ce/NiO was the most efficient catalyst in promoting the formation of Ni under the CO atmosphere.

Direct formic acid fuel cells (DFAFCs) have become an important technology and a clean energy source for various applications. However, some drawbacks in DFAFC applications, such as sluggish kinetics of formic acid oxidation (FAO) reaction at the anodic side, significantly affect DFAFC performance. An excellent catalyst, platinum (Pt), is very effective and performs excellently in FAO, but it is expensive and tends to form carbon monoxide-poisoning species on the catalyst surface. Therefore, new strategies must be developed to overcome problems related to Pt and simultaneously reduce or replace the use of Pt catalysts. This review paper covers the electrocatalytic activities of platinum and palladium (Pd)-based catalysts, which are commercial catalysts and effective for FAO and DFAFC applications. In this paper, the current progress of electrocatalyst development for anodic FAO and DFAFC applications using commercial Pt and Pd catalysts is presented, focusing on the understanding of Pt and Pd catalytic activities with the addition of alloys, metallic metals, trimetallic/tetrametallic metals, transition metals, and metal oxides. Highly potential nanostructured carbon catalyst supports (graphene-based materials, carbon nanotubes, carbon nanofibers, and graphitic carbon nitride) for FAO and DFAFC applications are also discussed. This review article also examines the literature related to Pt and Pd electrocatalysts on the synthesis routes, electrochemical conditions, and fuel cell performance within 10 years from 2013 until 2023. The challenges and strategies for electrocatalyst commercialization in the field are discussed at the end of the paper.

This comprehensive review article highlights recent advancements of Pt and Pd-based electrocatalysts, covering Pt and Pd alloys, Pt-M and Pd-M core-shell structures, nanosize/nanostructure effects, addition of support material, doping effects, and post-treatment for the oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) in Proton exchange membrane fuel cell (PEMFC). Additionally, it delves into other precious metals such as Gold (Au) and Silver (Ag) for ORR and HOR in PEMFC. The role and contribution of incorporating other elements or materials such as metal oxides, metal carbides, transition metal oxides, carbon support, and non-carbon support are thoroughly discussed. The most promising methods are also described, with a special emphasis on narrow particle size, nanostructure, and low loading of novel Pt- and Pd-based catalysts. Furthermore, the advantages and shortcomings of these catalysts for electrocatalysis are analyzed, along with the influence of the nanostructure and morphology of the electrocatalyst materials on electrochemical performance.

Termitomyces sp. mushroom is an edible mushroom that belongs to the family of Lyophyllaceae and exhibited growth associated with termites in a symbiotic environment. In this study, Termitomyces sp. mushroom was isolated from several places located in Negeri Sembilan, Malaysia namely TM 1 (Senaling, Kuala Pilah, TM 2 (Batu Kikir, Kuala Pilah) and TM 3 (Rembau Negeri Sembilan). The collection process was conducted during the early rainy seasons within October to November in which these mushrooms were actively growing. The collected mushrooms fruiting bodies from the wild were further used in tissue culture for the growth of mycelium on the agar medium. Out of the three samples only TM 1 mycelium were successfully grown on the agar medium and subsequent optimization were carried out to enhance the growth of the TM 1 mycelium. The composition of the agar medium was manipulated, and it was observed that the combination of PDA (potato dextrose agar) + ME (malt extract) + YE (yeast extract) showed a thick full plate growth of mycelium in 14 days of cultivation. The mushroom mycelium of TM 1 was able to grow and produce polysaccharide in batch submerged liquid fermentation with a biomass of 8.55 g/L, intracellular polysaccharide (IPS CWE and IPS HWE) of 1.36 and 3.20 g/L respectively and extracellular polysaccharide of 1.44 g/L.

This study aimed to investigate the influence of added chromium on the physical and chemical reduction behavior of molybdenum trioxide (MoO3) in a carbon monoxide (CO) environment. The reduction behavior of the sample was evaluated by using temperature-programmed reduction (TPR), and the phases produced by the reduced samples were analyzed using X-ray diffraction spectroscopy (XRD) and field emission scanning electron microscopy (FESEM). The TPR study was conducted using two reduction modes: non-isothermal reduction at 700°C with 20 vol. % of CO in nitrogen (N2), followed by isothermal reduction at 700°C for an additional 60 min. The TPR profile showed that the reduction of doped and undoped MoO3 was preceded by two reduction stages (MoO3 → Mo4O11 → MoO2), wherein, the reduction of doped MoO3 starting at a lower temperature (380°C500°C) than that of undoped MoO3 (550°C). Additionally, based on XRD analysis, it was shown that the conversion of MoO3 to MoO2 under CO generated an intermediate product known as Mo4O11. It is discovered that, increasing the concentration of chromium doped to MoO3 enhanced the reducibility of oxide due to the rapid production of MoO2 phases at T: 380ºC. Further heating under CO atmosphere, carbide species built up in the form of Mo2C rather than metallic Mo which might be due to excess of CO exposure to the surface layer of oxide.

The reduction behavior of cerium nickel oxide (Ce/NiO) catalyst was investigated by using temperature programmed reduction (TPR) with exposure of 40% (v/v) carbon monoxide (CO) in nitrogen atmosphere as a reductant agent. The Ce/NiO catalysts were prepared by using the conventional impregnation method. The reduction characteristics of NiO to Ni were examined up to 700 ºC and followed by isothermal reduction. The TPR profiles of doped NiO slightly shifted to a lower temperature from 375 to 366 ºC when Ce loading was increased from 3% to 10% (wt./ wt.), respectively. Whereas the undoped NiO was reduced at a higher temperature of 387 ºC. XRD diffractogram of the catalysts showed a complete reduction of NiO to Ni. The interaction between cerium and nickel ions for Ce/NiO series leads to a slight decrease in the reduction temperature. Fine sharp particles of Ce deposited on the NiO surfaces were observed through the FESEM images indicating some morphology modification occurred on NiO. It was found that the addition of 10% (w/w) of Ce on NiO also exhibited a larger BET surface area (11.31 m2g-1) and a smaller average pore diameter (17.7 nm). Based on these results, it is interesting to note that the addition of Ce to NiO has a remarkable influence in reducing the temperature of the reduction process. The 5% Ce/NiO was found sufficient to enhance the reducibility of NiO at a lower temperature.

Direct methanol fuel cells (DMFC), among the most suited and prospective alternatives for portable electronics, have lately been treated with nanotechnology. DMFCs may be able to remedy the energy security issue by having low operating temperatures, high conversion efficiencies, and minimal emission levels. Though, slow reaction kinetics are a significant restriction of DMFC, lowering efficiency and energy output. Nowadays, research is more focused on fundamental studies that are studying the factors that can improve the capacity and activity of catalysts. In DMFC, among the most widely explored catalysts are platinum and ruthenium which are enhanced in nature by the presence of supporting materials such as nanocarbons and metal oxides. As a result, this research sheds light on nanocatalyst development for DMFCs based on Platinum noble metal. To summarize, this research focuses on the structure of nanocatalysts, as well as support materials for nanocatalysts that can be 3D, 2D, 1D, or 0D. The support material described is made up of CNT, CNF, and CNW, which are the most extensively used because they improve the performance of catalysts in DMFCs. In addition, cost estimations for fuel cell technology are emphasized to show the technology's status and requirements. Finally, challenges to nanocatalyst development have been recognized, as well as future prospects, as recommendations for more innovative future research.